Family name วันจา (Wanja 
, วันจา 
, Wanjah 
) , worldwide, is a common cognomen. The surname วันจา is characteristic of Kenya, where it is quite a common surname, United Arab Emirates, where it is quite a rare surname, and Qatar, where it is a rare surname. In absolute terms, it is the most numerous in Sub-Saharan Africa, particularly Kenya, the Democratic Republic of the Congo, and Cameroon. Much less frequently, วันจา is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Wanja | Kenya, Tanzania, Germany, Cameroon, United Arab Emirates |
| วันจา | Thailand |
| Wanjah | Kenya, Nigeria, South Africa, Thailand, India |
| Whanja | Democratic Republic of the Congo, United States |